Effect of characteristics of media on cobalt and iron nanoparticles prepared by arc discharge method

Above a critical size, cobalt (Co) and iron (Fe) nanoparticles (NPs) aggregate due to magnetic dipole–dipole interaction into chains. In this paper, the effect of liquid environment on nucleation, growth and aggregation of Fe and Co nanoparticles is reported. The iron NPs were prepared by novel arc discharge method in ethylene glycol and 1-propanol and the cobalt NPs were prepared by that method in five liquid environments: ethylene glycol, 1-propanol, ethanol, methanol, and deionized water. SEM and FE-SEM observations were employed for morphology of the NPs. Meanwhile, in this case, the effect of media was discussed by considering the characteristics of the solution such as size, shape and dipole moment of its molecules. Preparation of Fe results shows that compared to 1-propanol a denser agglomeration can be seen among the NPs dispersed in ethylene glycol and the NPs possess a broader size distribution. Preparation of Co NPs in five solvent results if a solvent has large molecules with small dipole moment then the NPs will be larger in size. When three different amounts of surfactant PVP is added to prepared Fe nanofluid, it can be concluded that a low PVP content leads to more uniform NPs with rather clear boundaries.